The common definition for the eye may come around as “what animals and humans use to see”, but this is not the case for all organisms on Earth. Some organisms use their eyes as light detecting pits, for swallowing, and some have eyes under their skin. Compared to multiple animals, the human eye may seem as one of the simpler ones in our ecosystem.
Dan-Eric Nilsson, a biologist from Lund University, began doing research upon Tripedalia cystophora, or Box Jellyfish, and the way that they utilize their eyes. What Nilsson discovered was quite intriguing; the Box Jellyfish has 24 total eyes, each group into sets of six, called rhopalia. Since the jellyfish is only made of three layers, the epidermis, the mesoglea, and the gastrodermis, the eyes have to be rooted by a flexible stalk-like structure. Two of the six eyes in each rhopalia are more like human eyes; the jellyfish can use them to see through optic lenses. The remaining four eyes are light detection pits, so the jellyfish can gather more light in the dark depths of the ocean. The top eyes on the rhopalium can also be used for direction in water. when the eyes detect bright light, the Box jellyfish knows that it is swimming in open water upwards, risking its survival, but when dark patches appear the jellyfish realizes it is swimming downwards, towards the ocean floor for food. In a way, this brainless and bloodless organism uses its eyes to survive.
The Northern Leopard Frog is one of the most interesting creatures to ever exist, and utilizes its eyes in a unique fashion. Some frogs do not have enough muscular strength in their throats to swallow the kind of food they eat, so they are able to use their eyes to force food down their throat. If one ever observes a Leopard frog devouring its food, they notice that the frog closes its eyes while swallowing. The reason for this is because the eyes are retracting into their head so that the optic muscles can force food down their throats. Since the frog’s skeletal structure does not really pose a neck like part, food tends to travel any direction it wants to pass the mouth, so the frog uses cranial positioning, eyes, and tongue to feed. Even though this ideology has not become an obsolete fact, research at multiple institutes all over the globe have been closely monitoring these amazing amphibians.
The last animal which exploits its eyes in a sui generis fashion is the Notoryctes typhlops, or Southern Marsupial Mole. Native to central Australia, this burrowing critter’s eyes are located under its skin. Since the animal’s natural habitat is typically underground, over time, their eyes have become vestigial (evolutionary concept). In current times, the mole uses the front of its face and “blindness” to sense which direction it is traveling underground.
The bodily structures we share with other species throughout the planet all have a vivid array of functions, some more unique than others. We automatically assume that our human system holds the ultimate form of complexity, not knowing that the other 8 million species all have their own intricacy of systems within their bodies.